Method of making intaglio printing plates



Nov. 10, 1936. Q ,5, S AW 2,060,640

METHOD OF MAKING INTAGLIO PRINTING PLATES Filed Dec. 17, 1934 INVENTOR.

mar/ea P. film ATTORNEYS Patented Nov. 10, 1936 UNITED STATES PATENT OFFICE METHOD OF Charles P.

MAKING INTAGLIO PRINTING PLATES Shaw, Detroit, Mich, asslgnor to Detroit Moulding Corporation, Detroit, Mich.

Application December 17, 1934, Serial No. 757,792

13 Claims.

Third, to provide an improved intaglio printing plate which is especially well adapted for use in the reproduction of wood grain effects by offset printing.

Objects relating to details and economies of my invention will appear from the description to follow. The invention is defined and pointed out in the claims.

Certain steps of my method are illustrated in the accompanying drawing, in which:

Fig. 1 is a view in front elevation of the copy or subject to be reproduced.

'Fig. 2 is a view in front elevation of the continuous tone negative of the subject.

Fig. 3 is an enlarged view'in end elevation of the continuous tone negative and the positive arranged for contact exposure.

Fig. 4 is a view in front elevation of the continuous tone positive transparency.

Fig. 5 is a diagrammatic top plan view showing the apparatus arranged to carry out the fourth step of my method.

Fig. 6 is a greatly enlarged fragmentary plan view of the screen negative resulting from the high light exposure.

Fig. 7 is a similar view of the screen negative resulting from the middle tone exposure.

Fig. 8 is asimilar view of the screen negative resulting from the shadow exposure.

1 Referring to the drawing, the subject I to be transparency 6. The positive transparency so obtained is' intensified, retouched and corrected to bring out the desired tones and details.

I next place the transparency 6 in front of the camera I, the face of the transparency or the side having the emulsion of the positive 4 facing the camera lens. The transparency 6 is lighted from the back by light reflected from the white reflector 8, the light originating in rays 'B'from a light source notv shown. The reflected light rays ill from the reflector are diffused and broken up relative to the light rays 9, and in addition, the

reflected light rays are somewhat diffused and refracted by the glass transparency 6, the refracted light rays being shown at H.

The positive 4 on the transparency 6 is arranged to face the lens of the camera in order 5 not to get too much refraction of light. On account of the light penetrating through the transparency and on account of the slight grain of the emulsion, I obtain a very much richer and more varied tone, as well as cleaner cut detail 10 my indirect method reserves. all of the softness,

contrast and detail of the original- Where fiat subjects are photographically copied in the foregoing manner, there is a decided gain in life and I in tone values.

The camera is set for the exact size or less of the positive, and operates to concentrate the difiused light, and reproduces on the sensitized plate I2 sharp detail and a great variety of tone, in the same manner as when photographic copy is considerably reduced in size to bring out its sharpness. A ruled screen I3 is placed in the camera to produce a screened negative ii on the plate I2.

In making the screen negative I4, I use three definite exposure steps to bring out high lights, 80 middle tones, and shadows. Very satisfactory results may be had by observing the following directions. To make the high light exposure, use an F16 stop, which is a fairly large aperture, for a period of three minutes. sure may be for three and one-half minutes with an F32 stop or aperture, which is about one-half the size of the F16 stop. In the third and final exposure, a No. 15 stop may be used, the time of exposure being six minutes. A No. 15 stop is 40 about one-fourth the size of an F32 stop.

' The first high light exposure produces practically a black and white negative I5, Fig. 6, the blacks I6 being solid except for occasional lights I I, and the high lights I8 being very pronounced. This may be designated the first stage in the production of the screen negative. The middle tone exposure produces a second stage, Fig. 7, in which some of the blacks have been converted into middle tones l9 and some of the high light dots 20 have become smaller. In the third and last stage, Fig. 8, more of the blacksare changed to middle tones and moredetail is injected into the black; the high light dots are small and the whole subject is grayer and less contrasting, 56

The next expo- 35 This insures softness and the correct difference in depth of the dots or pockets after etching.

The screen negative so produced is converted into a positive (not shown), a print of such positive being made on a metal plate (not shown) having a sensitized surface which'is subsequently etched in a known manner. Since very little depth is required, the etching time is preferably short. The resulting intaglio printing plate is divided into cells of greatly varying area, the depth of the cells being directly proportional to their area. Some of the cells are connected, while others are unconnected, this being clearly shown by Fig. 8, the black dots in this case representing the cells.

My intaglio printing plate made in the foregoing manner is well adapted for offset printing owing to the great variety in the size of the cells which are adapted to carry the transfer ink. The various high light, middle tone, and shadow cells are relatively small and thus prevent slurring in the final reproduction which is faithful to the original and very attractive in appearance.

I have illustrated and described my improvements in an embodiment which I have found very practical. I have not attempted to illustrate or describe other embodiments or adaptations as it is believed this disclosure will enable those skilled in the art to embody or adapt. my improvements as may be desired.

Although I have shown and described a certain specific embodiment of my invention, I am fully aware that many modifications thereof are possible. My invention is therefore not to be restricted except insofar as is necessitated by the prior art and by the spirit of the appended claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. The method of making an intaglio plate for offset printing, which comprises the steps of making a continuous tone negative 'of the subject, converting said continuous tone negative into a positive transparency, modifying the tone and detail of said positive transparency, lighting the transparency by reflected light pasing through the transparency and being diifused and refracted thereby, making a screen negative of the transparency so lighted by exposure first with a fairly large stop for three minutes to bring out the high lights, then with a stop of one-half the size of the first for three and onehalf minutes to bring out the middle tones, and finally with a stop one-fourth the size of the second. for six minutes to bring out the shadows, making a screen positive from the screennegative, and making an etched intaglio printing plate from said screen positive, the exposures and etch ing being controlled so that the depth of the cells is directly proportional to their area.

2. The method of making an intaglio plate for offset printing, which comprises the steps of making a continuous tone negative of the subject, converting said continuous tone negative into a positive transparency, lighting the transparency by reflected light passing through the transparency, making a screen negative of the transparency so lighted by exposure first with a fairly large stop for three minutes to bring out the high lights, then with a stop of onerhalf the size of the first for three and one-half minutes to bring out the middle tones, and finally with a stop one-fourth the size of the second for six minutes to bring out the shadows, making a screen positive from the screen negative, and making an etched intaglio printing plate from said screen positive.

3. The method of making an intaglio plate for offset printing, which comprises the steps of making a continuous tone negative of the subject, converting said continuous tone negative into a positive transparency, lighting 'the transparency by reflected light passing through the transparency and being diffused and refracted thereby, making a screen negative of the transparency so lighted by successive exposures to bring out the high lights, middle tones, and shadows, making a screen positive from the screen negative, and making an etched intaglio printing plate from said screen positive, the exposures and etching being controlled so that the depth of each cell is proportional to its area.

4. The method of making an intaglio plate for offset printing, which comprises the steps of making a continuous tone negative of the subject, converting said continuous tone negative into a positive transparency, lighting the transparency by reflected light passing through the transparency and being difiused and refracted thereby, making a screen negative of the transparency, making a screen positive from the screen negative, and making an intaglio printing platefrom said screen positive;

5. The method of making an intaglio plate for offset printing, which comprises the steps of making a continuous tone negative of the subject, converting said continuous tone negative into a positive transparency, modifying the tone and detail of said positive transparency, making a screen negative of the transparency by suc cessive exposures first with a fairly large stop for three minutes to bring out the high lights, then with a stop of one-half the size of the first for three and one-half minutes to bring out the middle tones, and finally with the stop onefourth the size of the second for six minutes to bring out the shadows, making a screen positive from the screen negative, and making an etched intaglio printing plate from said screen positive, the etching being controlled so that the depth of the cells is directly proportional to their area.

6. The method'of making an intaglio plate for ofiset printing, which comprises the steps of making a continuous tone negative of the sub- J'ect, converting said continuous tone negative into a positive transparency, making a screen negative of the transparency by successive exposures with a fairly large stop for three minuts to. bring out the high lights, then with a stop of one-half the size of the first for three and one-half minutes to bring out the middle tones, and finally with a stop one-fourth the size of the second for six minutes to bring out the shadows, making a screen positive from the screen negative, and making an intaglio printing plate from said screen positive.

7. The method of making intaglio printing plates, which comprises the steps of making a. continuous tone positive transparency of the subject to be reproduced, lighting the transparency by reflected light with the emulsion of the positive transparency facing the lens of a camera, making a screen negative in said camera of the transparency so lighted, and making an etched intaglio printing plate from said negative, said plate having cells of greatly varying area whose depth is directly proportional to their area.

8. The method of making intaglio printing plates, which comprises the steps of maldng a continuous tone positive transparency of the subject to the reproduced, lighting the transparency by reflected light passing therethrough with the emulsion of the positive transparency facing the lens of a, camera, making a screen negative in said camera of the transparency so lighted, and making an etched intaglio printing plate from said negative.

9. The method of making intaglio printing plates, which comprises the steps of making a continuous tone positive transparency of the subject to be reproduced, lighting the transparency by reflected light, making a screen negative in said camera of the transparency so lighted, and making an etched intaglio printing plate from said negative.

10. The method of making intaglio printing plates, which comprises the steps of making a continuous tone positive transparency of the subject, making a screennegative of said transparency by successive exposures firstwith an'Fid stop for three minutes to bring out the high lights, then with an F32 stop for three and onehalf minutes to bring out the middle tones, and then with a No. 15 stop for six minutes to bring out the shadows, and making an etched intaglio printing plate from said screen negative, the plate being provided with cells of greatly varying area whose depth is directly proportional to their area.

11. The method of making intaglio printing plates, which comprises the steps of making a continuous tone positive transparency of the subject, making a screen negative of said transparency by successive exposures first with an F16 stop for three minutes to bring cut'the high lights, then with an F32 for three and one-halt minutes to bring out the middle tones, and then with a No. 15 stop for six minutes to bring out the shadows, and making an etched intaglio printing plate from said screen negative.

12. The method of making an intaglio plate for oifset printing, which comprises the steps of making a continuous tone negative of the subiect, converting said continuous tone negative into a positive transparency, lighting the transparency by reflected light passing through the transparency, makinga negative or the transparency so lighted by exposure first with a fairly large stop for three minutes to bring out the high lights, then with a stop of one-half the size oi the first for three and one-half minutes to bring out the middle tones, and finally with a stop onefourth the size of the second for six minutes to. bring out the shadows, making a positive from said last named negative, and making an etched 

